1. Field of the Invention
The invention relates to measurement of flow parameters and provides a desired flow to impinge on the sensing element at various stream flow rates.
2. Description of the Prior Art
Devices for sensing data in a flow stream which provide for accurate, fast response and ruggedness at relatively low cost are desirable. While certain devices may have been useful in the past, the advantages of the present device, as disclosed herein, are apparent.
In the prior art, U.S. Pat. No. 2,970,475 issued Feb. 7, 1961 and has the same assignee as the present invention. That patent provided for boundary layer control (BLC) for a gas temperature probe, thus increasing the capability of a temperature sensor to accurately read the total temperature of the fluid when brought to rest against the sensing element. In U.S. Pat. No. 3,512,414, also held by the same assignee as the present invention, further advantages of ruggedness, minimum drag, BLC and others are shown. The utility of inventions for such applications has been established by use for laboratory testing, and by extensive commercialization for air vehicles.
Recently, U.S. Pat. No. 4,152,938 issued. While this patent may appear to be somewhat similar to the present invention, it is stated at column 5, line 61, "Because the probe requires unobstructed flow through bore 14 the preferred structure . . . ". As herein disclosed, regulation of internal flow enhances operation, for example, where the fluid is air, regulation of flow enhances operation at Mach numbers above 0.5. No means, method or the desirability of such means or method for regulation is disclosed in U.S. Pat. No. 4,152,938. Other advantages are apparent from the invention as herein disclosed.